Enamelware produced by firing dry enamel powder in contact with a glass fiber fabric



United States Patent 3,544,352 ENAMELWARE PRODUCED BY FIRING DRY ENAMEL POWDER IN CONTACT WITH A GLASS FIBER FABRIC William C. Cawthon, New Canaan, Conn., and Robert J. Ulrich, Lyndon, Ky., assignors to American Standard Inc., New York, N.Y., a corporation of Delaware No Drawing. Original application Mar. 7, 1966, Ser. No. 532,090, now Patent No. 3,453,133, dated July 1, 1969. Divided and this application Feb. 14, 1969, Ser. No. 817 212 Int. Cl. B44d 1/094; B44c 1/04; C23d 5/04 US. Cl. 11723 2 Claims ABSTRACT OF THE DISCLOSURE Method for producing an enamelware article having a patterned surface which involves applying to an object to be enameled a coating of dry enamel powder, placing in contact with the coating a glass fiber cloth, and firing the dry enamel powder and the glass fiber cloth in contact therewith.

This is a division of United States patent application Ser. No. 532,090, filed Mar. 7, 1966, now US. -Pat. No. 3,453,133, issued July 1, 1969.

This invention relates to enamelware. More specifically, this invention relates to methods for applying useful and decorative surface finishes to enameled articles or portions thereof.

In many applications of enameled articles, the glossy surface normally characteristic of such articles is objectionable for one reason or another. In architectural applications, it may be desired to provide a matte finish for esthetic reasons or, particularly in exterior environments, to prevent objectionable glare from the glossy surface. In other cases, particularly in the production of bathtubs, shower floors and the like, the smoothness of the normal glossy surface is objectionable because of the hazard of slippage. Various methods have heretofore been proposed for developing matte or roughened surfaced on enameled articles, but in some cases they were less than wholly successful for a variety of reasons. In general such methods resulted in the production of a surface characterized by minute surface irregularities. If, however, these irregularities were sufliciently large in size to afford any effective degree of non-skid action, they produced an undesirable sandy or unfinished appearance, and tended to trap and hold dirt, so that cleaning was difiicult.

Various methods have also been proposed for application of decorative colored designs to enameled surfaces. These have included a number of methods which involved the initial preparation of a liquid suspension of colored oxides, which could subsequently be applied either to fired or to unfired enamelware, and subsequently fired on. Other processes involved the application of the colorants in dry powder form to a fired or unfired piece, with an undercoating of fixative or the like, if needed, to hold the powdered colors in place until firing. All of these methods, essentially, required that the design be formed directly on the enamelware article, either by painting, stencilling, or the like. In applications requiring the use of several colors, it is generally necessary to apply the liquid or solid colorants to the workpiece one at a time, one over the other, frequently with extra drying or firing steps in between applications of the various colors. A mistake in positioning of any one of the colored elements of the design could destroy the design to the extent that it could not be economically salvaged.

Moreover, in virtually all of the methods heretofore proposed, additions of any kind, whether in the nature of colorants or skid-resisting materials, were necessarily made while the workpiece was at or near normal room temperature. This is undesirable because of the resulting increased demand on fuel and furnace capacity involved in cooling a fired piece to room temperature and then, after application of the additive, reheating it to firing temperature. It is additionally undesirable because the additional heating and subsequent cooling of the piece increases the possibilities for development of strains which may lead to cracking or spalling of the finish, resulting in rejects.

An object of this invention, therefore, is to provide improved methods for producing non-skid surfaces on enameled articles.

Another object is to provide methods for producing such non-skid surfaces, which do not at the same time produce an undesirable sandy or unfinished appearance.

Still another object is to provide such methods, which provide readily cleanable non-skid surfaces.

A further object is to provide improved methods for the application of designs and indicia of various kinds to enamelware surfaces.

Another object is to provide methods for application of multicolor designs and indicia to enamelware surfaces, which avoid the necessity of building up a design by successive applications of different colorants.

Yet another object is toprovide methods whereby designs may be created on a carrier separate from the enameled article, and subsequently transferred to said enameled article.

Another object of the invention is to provide a method whereby the transfer of colorants and/or antiskid materials to the workpiece may be made while the workpiece is at an elevated temperature.

A feature of the invention is the use of glass fiber cloth as a medium for imprinting a non-skid pattern in the surface of an enameled article.

Another feature is the application of glass fiber cloth to an enameled article bearing one or more fired coats of enamel and an unfired coat of enamel material, and firing the unfired coat in contact with the glass fiber cloth.

Still another feature resides in the application of a ceramic colorant to an enamel by applying to said enamel while still in the unfired condition, a glass fiber cloth bearing said colorant and firing said enamel while in contact with the glass fiber cloth and the colorant thereon.

Other objects, features and advantages will become apparent from the following more complete description and claims.

In one particularly desirable embodiment, this invention contemplates an article of enamelware having a surface, at least part of said surface having a patterned texture corresponding to the texture of a cloth fabric.

In another particularly desirable embodiment, this invention contemplates a method for producing an enamelware article having a patterned surface, comprising the steps of applying to an object to be enamaled a coating of dry enamel powder, placing in contact with said coating a glass fiber cloth, and firing said dry enamel and said glass fiber cloth in contact therewith.

In still another embodiment, this invention contemplates a method for producing an enameled article having thereon a design of a color different from the color of the enamel, comprising the steps of applying to an object to be enameled a coating of dry enamel powder, placing in contact with said coating a glass fiber cloth having a ceramic colorant thereon, and firing said enamel coating and said glass fiber cloth and colorant in contact therewith.

The articles and methods of this invention are particularly useful in connection with bathtubs, shower floors and the like, where the patterned or textured surface is advantageous for itsnon-skid properties. It is also useful in many other applications, simply for the pleasing appearance created by the duplication in the fired enamel surface, of the texture and pattern of the glass fiber cloth. In either type of application, the appearance of the article may be enhanced by using the glass fiber cloth as a medium for applying colorants to the article, either in the form of a single overall color coextensive with the textured portion of the surface, or as a design in one or more colors, which may be placed initially on the glass fiber cloth and transferred from the cloth to the enamelware article during firing.

The methods of this invention are applicable to enamelware articles generally, and an article which is to receive only a single coat of enamel may be treated so that the single enamel coat is textured by firing it in contact With glass fiber cloth. In accordance with-conventional practice, however, it is more usual toapply one or more coats of enamel prior to application of the textured finish coat. For example, an article of metal, such as a bathtub, may be coated initially with a base coat, which is fired on. The base coat maybe applied wet, in the form of a slip. The base coat is then dried and fired on. Finally, the finish coat is applied. The finish coat is preferably applied by dry techniques, as the dry method reproduces the texture of the glass cloth in greater detail. The glass cloth, with or without colorants, as the case may be, is pressed lightly into the unfired finish coat of enamel powder, and left in place during the firing. During the firing operation, the glass fiber cloth disintegrates. It apparently remains intact long enough, however, so that its texture is permanently imprinted into the surface of the finish coat. On completion of the final firing, and cooling, the disintegrated remains of the glass fiber cloth are removed by brushing or other means to prevent injury to persons using the product.

The particular composition of the enamel used is not critical to the success of the invention, and any of the conventional enamel formulations may be used successfully.

By the same token, the particular glass fiber cloth is not a critical matter. Good results have been achieved using relatively coarse grades of cloth designed for industrial filtration or construction of fiberglass-reinforced plastic structures such as boat hulls and the like. Examples of such materials include Iohns-Manville .032 cloth and J ohns-Manville .016 cloth. Equally good results have been obtained using fibrous glass drapery materials such as are used for interior decorating, these giving, as might be expected, a much finer textured surface. The glass fiber cloth may be either woven or knitted, although a majority of commercially available glassfiber cloths are of the woven variety.

When the method of this invention is used to produce colored designs on the textured surface, any of the conventional materials commonly used for coloring ceramic objects may be used. In many cases, these are materials which are also used for dying glass fiber cloth, such as iron oxides, cadmium salts, and various other inorganic pigments well known to the art. When applied to glass fiber cloth, such oxides are customarily bonded to the glass fibers by the use of a suitable resin or other appropriate adhesive. This invention may be practiced by using appropriate commercial glass fiber materials already bearing the desired colors or designs, provided the materials used to color the materials are stable at the temperatures used for firing the enamelware. In the course of the firing, the binder is burned off, and the pigment is transferred from the glass fiber cloth to the surface of the enamel. If desired, the invention may also be practiced by starting with plain glass cloth and applying the coloring oxides thereto in any convenient manner such as the conventional methods for applying colorants to glass cloth materials, and the resulting colorant-bearing glass cloth used in the same way as above described.

The glass fiber cloth may be simply laid on the unfired enamel surface, or it may be pressed down lightly to fix it in place and help assure faithful reproduction of the cloth texture in the enamel.

After the glass fiber cloth is in place, the article is fire in a conventional firing cycle depending on the composition of the enamel. No change in firing conditions is necessitated by the presence of the glass cloth, although when the glass cloth is used to apply colors to the article, the nature of the particular colorant selected may require some adjustment in firing conditions, as will be obvious to those familiar with such colorants and their application to enamelware articles.

Although the particular type of glass fiber cloth is subject to wide latitude depending on the effects desired, it is apparently necessary to employ a glass cloth. Similar materials such as asbestos cloth, which might be expected to show similar results, fail to produce a non-skid textured surface.

In order to illustrate more fully the nature of this invention and the manner of practicing the same, the following examples are presented.

EXAMPLE I A typical enamel composition can be prepared by mixing, fusing and grinding, according to conventional techniques, the following ingredients:

Cover coat enamel formula Parts by weight Borax, anhydrous 44 A cast iron workpiece, for example a lavatory basin, is provided with a conventional base coat and the base coat is fired in a furnace for an appropriate time at an appropriate temperature to properly mature the base coat, for example, for 10 minutes at 1725 F.

The workpiece is then removed from the furnace and (while still hot) is covered with a cover coat of dry, powdered cover enamel of the above composition, applied by dusting from a sieve. The workpiece is then returned to the furnace and heated sufliciently to melt the enamel coat to a smooth, glossy surface.

The workpiece is again removed from the furnace and a second cover coat of dry, powdered cover enamel is applied in substantially the same manner as the first cover coat, after which a glass fiber cloth is placed in contact with the portion of the workpiece to be textured, and the workpiece with the glass fiber cloth is returned to the furnace and fired in the same manner as for the first cover coat.

After the firing of the second cover coat, the workpiece is removed from the furnace and allowed to cool. The textured portion of the workpiece is brushed lightly to remove the loose flakes of material remaining from the disintegration of the glass fiber cloth. The portion of the workpiece which has been fired, in contact with the glass fiber cloth has a textured, non-skid, easily cleanable surface of pleasing appearance corresponding to the texture of the glass fiber cloth.

EXAMPLE 2 The procedure of Example 1 is repeated, except that the glass fiber cloth is not applied to the iecond cover coat prior to firing thereof. Instead, the second cover coat is fired in the same manner as the first cover coat. The workpiece is then removed from the furnace, the fiberglass is applied to the desired portion of the workpiece, and the workpiece is returned to the furnace and lightly fired, sufficiently to permit the texture of the glass fiber cloth to be impressed into the surface of the second cover coat. The workpiece is then removed from the furnace, cooled and brushed as described in Example 1. The resulting product is similar to that produced according to Example 1.

EXAMPLE 3 The procedure of Example 1 is repeated, except that the glass fiber cloth employed is a tinted cloth, colored blue by the use of a cobalt-chromium composition. The resulting textured workpiece is similar to that produced according to Example 1, except that the cobalt-chromium is transferred to the enamel during the firing of the second cover coat, and the finished workpiece is colored blue in the textured area.

While this invention has been described with reference to certain preferred embodiments of the invention, these are illustrative only, as many alternatives and equivalents will readily occur to those skilled in the art, without departing from the spirit or proper scope of the invention.

The invention is therefore not to be construed as limited, except as set forth in the following claims.

What is claimed is:

1. An article of enamelware having a textured enamel surface coating, at least part of said surface coating having a patterned texture produced by firing dry enamel powder in contact with a glass fiber fabric.

2. An article of enamelware according to claim 1, wherein said part of said surface having a patterned texture is of a color differing from the color of the remainder of said surface.

WILLIAM D. MARTIN, Primary Examiner R. M. SPEER, Assistant Examiner US. Cl. X.R. 

